Coil and spool and an improved method of making a coil



Jall- 1968 J. s. HOLLYDAY 3,363,210

COIL AND SPOOL AND AN IMPROVED METHOD OF MAKING A COIL Filed July 6,1965 United States Patent 3,363,210 COIL AND SPOQL AND AN IMPROVEDMETHOD OF MAKING A COIL Joseph S. Hollyday, Pennington, NJ, assignor toHeinemann Electric Company, Trenton, N..'l., a corporation of New JerseyFiled July 6, 1965, Ser. No. 469,590 12 Claims. (Cl. 336-485) ABSTRACTBE THE DISCLQSURE This invention provides a spool for a relay coil whichhas a channel at one end defined by two flanges, the channel beingnotched at the entry end to define for a starting end wire a sideentrance to the channel and the channel receiving lead wires which arewedged into the channel so that any mechanical pull on the lead wires istransmitted to the spool.

Background of the invention An electrical coil, particularly a voltagerelay coil, that is, a relay coil which has substantially the fullvoltage of the circuit across the coil is subjected to high dielectricstresses and this is especially true during overvoltage surges. Thepoint of maximum voltage stress is the point where the windings startingend wire passes by the other layers of the winding. Since the insulationof the wires of a winding of a coil is kept to a minimum, an electricalbreakdown may occur at this point between the starting end wire and theother windings of the coil. Further the leads of the coil may besubjected to a mechanical pulling or twisting during handling andinstallation. It is, therefore, an object of this invention to providean improved coil arrangement for minimizing or preventing theaforementioned electrical breakdown and for securing leads to the wireforming the winding, and arranging them relative to the spool, togetherwith an improved spool construction, so that any mechanical forceimposed on the leads will be substantially transferred to the spool.

Summary of the invention In this invention, the starting end wire of thewinding and the starting lead wire is inserted in a channel formed atone end of the spool between two flanges. The channel is open to themain portion of the spool at the level of the inner layer of thewinding. Thus, the starting end wire and the starting lead wire areseparated from the upper layers of the winding by the inner of these twoflanges whose thickness and material, preferably nylon, is suflicient towithstand any voltage stress that may occur. Further, no abrasion of thestarting end wire can occur as the inner flange effectively separates itfrom the end turns of the winding.

As is the custom in the prior art, it is common to attach to the endwires of the winding, because they are i usually of small diameter,wires of much greater diameter and with thicker insulation, commonlycalled leads. This is done to provide leads which will be resistant tobreaking due to tension, twisting, crushing or other mechanical abuseand to get higher resistance to dielectric break down between them. Inthis invention, the lead wires are placed in the channel formed by thetwo flanges of the spool and the channel is turned upon itself and sincethe flanges, in the preferred embodiment, are approximately rectangular,the channel forms approximately a three quarter turn around the spool.The insulation of the lead wires is of such a size that the lead wiresfit the channel tightly and are preferably taped in place. Thus, anymechanical pull on the lead wires is transmitted to the spool, becauseof the tight fit and the three-quarter 3,363,210 Patented Jan. 9, 1968turn, and the spool is of suflicient size and strength to resist thispull.

The foregoing and other objects of the invention, the principles of theinvention, and the best mode in which it is contemplated applying suchprinciples will more fully appear from the following description andaccompanying drawings in illustration thereof.

Brief description of the drawings In the drawings,

FIG. 1 is a front elevation illustrating a spool incorporating thisinvention;

FIG. 2 is a side view, taken along the line 22 in FIG. 1;

'FIG. 3 is a partial back view of the spool illustrated in FIG. 1, takenalong the line 33 in FIG. 2;

FIG. 4 is a perspective and partly diagrammatic view with a portion ofthe spool being cut away to illustrate initiation of the winding of thewire onto the core;

FIG. 5 is a view similar to FIG. 4, but illustrating the spool and thewinding after the finishing lead has been secured to the finishing endwire;

FIG. 6 is a view similar to FIGS. 4 and 5, but illustrating the coilafter the starting lead wire has been secured to the starting end wire;

FIG. 7 is a view similar to FIG. 6, but illustrating the coil after thestarting lead wire and finishing lead wire have been placed in thechannel but before the channel has been completely covered by aninsulating tape; and

FIG. 8 is a partial sectional view taken along the line 8-8 in FIG. 7.

Description of the preferred embodiment Referring to the drawings, FIGS.1, 2 and 3 illustrate a spool or bobbin '10 of electrical insulatingmaterial, preferably nylon, of a coil 21, FIG. 7. The spool 16 comprisesa hollow spindle or core 12 having a flange 14 at the left hand end, asviewed in FIG. 1, and a pair of tfianges 16 and 18 at the opposite,right hand end, as viewed in FIG. 1. V

The outer surface 19 of the core and the opposed surfaces of the flanges14 and 16 define a space for receiving a suitable number of turns ofinsulated wire to form a winding 20, FIGS. 4 and 5.

The flanges 16 and 18 with a bottom wall 213 define an elongated channel25 in which are receivedstarting and finishing lead wires 27 and 29,respectively. The channel 25 has open ends 40 and 41 and is also openalong its peripheral (radially outermost) extent, as shown in thedrawings.

The flanges 14, 16 and 18 are all integral with the core 12, the core 12and the flanges 14, 16 and 18 being generally rectangular in crosssectional shape. The flange 14 is complete in a peripheral sense, butthe flange 16, however, is cut away at one corner to form a notch 31defining an entry for the windings starting end wire 33 into the channel25. One of the shorter sides of the flange 18 may be omitted, asillustrated, and the bottom wall extended, as at 30 and 32, to form arecess 35, so that part of the magnetic laminations (not illustrated)with which the coil 21 is associated may be received in the recess 35.

The bottom wall 23, which connects the flanges 16 and 18, extendsgenerally at right angles to the flanges 16 and 18, The wall 30 has anentry surface 36 which is coplanar with one of the surfaces, the surface37, of the core 12, and the surface 36 is joined to the main surface 44of the wall 23 by an inclined surface 45.

The winding 20 of insulated wire is formed on the spool 10 by taking thewindings starting end wire 33 and placing it in section A of the channel25, as illustrated in FIG.

4, and a part of the starting end wire 33 is temporarily taped to theflanges 16 and 18, as shown by the tape 50.

The starting end wire 33 is placed on the bottom wall 23 of channelsection A, upon the entry surface 36, and is wound about the surface 19of the core in the direction indicated by the arrow in FIG. 4 for asmany turns as is desired. After a sutficient number of turns of wirehave been wound about the core, an elongated flat, thin insulator tape52 is placed on the winding 20 as shown. At one end of the winding 20the windings finishing end wire 53 is taped in place upon the insulator52 by a narrow piece of insulating tape 56. The finishing end wire 53 istaped in place by the tape 56 with a length of the finishing end wire 53extending upon the insulator 52. The extreme left end of the lead wire29 is then soldered to the finishing end wire 53. Thereafter, the leadwire 29 is taped to the winding by the first turn of the tape 60. Themajor portion of the lead wire 29 being free, as shown. In FIGS. 5 and6, for case of illustration, the lead wire 29 has been foreshortened, asindicated at D.

Thereafter, referring to FIG. 6, the temporary tape 50 which secured thestarting end wire 33 to the flanges 16 and 18, shown in FIG. 4, isremoved. The windings starting end wire 33 is then cut to proper length,if necessary, and soldered to the starting lead wire 27.

The starting lead wire 27 and. the starting end wire 33 are long enoughso that the soldered joint between them can be made outside of thechannel 25. After the starting end wire 33 has been soldered to thestarting lead wire 27, the starting end wire 33, the soldered joint andthe starting lead wire 27 are placed in the channel25, as illustrated inFIG. 6. The solder connection between the starting end wire 33 and thelead wire 27 is placed in the channel section A to the right of thenotch 31 so that it is separated from the windings by the flange 16 toprevent abrasion of the windings by the soldered joint. The end wire 33comes off of the solder connection at the latters right hand end so thatthe end wire 33 loops, as shown in FIG. 6.

The starting lead wire 27 is first placed in the channel section A andthen placed sequentially in channel sections B and C. On top of thestarting lead wire 27 is placed the finishing lead wire 29, asillustrated in FIG. 8. The winding 20 is then covered with a suitablenumber of turns of the insulating tape 60, FIG. 7. Preferably, theflanges 16 and 18 are also covered with turns of the insulating tape 60,and FIG. 7 shows the flanges 16 and 18 about to be covered.

The channel 25 is of rectangular cross sectional shape, FIG. 8, and deepenough so that the two lead wires 27 and 29 may be placed one on top ofthe other within the channel 25 with no part of the upper lead wire 29extending substantially beyond the (radially outermost) peripheralsurfaces of the flanges 16 and 18. Since the channel 25 is deeper at theinclined surface 45, a pocket is provided to receive the soldered jointbetween the starting end wire 33 and the lead wire 27 so that thesoldered joint is slightly spaced from the adjacent portion of the leadWire 29. It is seen in FIG. 7 that the end wire 33 is spaced below theadjacent overlying portion of the lead wire 29. Thus, abrasion betweenthe soldered joint and the lead wire 29 is minimized.

Further, by inclining the wall 45, as illustrated, a wall of greaterthickness results between the flanges 16 and 18 than if the thickness ofthe extension 30 was continued for the entire length of the wall 23.Also, by raising the surface 44 relative to the surface 36, the upperpart, as viewed in FIG. 8, of the lead wire 29 is exposed to the tape60, assuming the tape 60 is placed across the flanges 16 and 18, tofurther strengthen the coil.

The width of the channel 25 is such that the leads 27 and 29 are snuglyand tightly received within the channel. Preferably, a small amount offorce is required to press the leads 27 and 29 down into the channel,the outside diameter of the insulation of the leads 27 and 29 being justslightly greater than the width of the channel. After the leads areplaced in the channel, or before, the leads 27 and 29 are cut to lengthto suit and connector lugs may be soldered to them, but are notillustrated.

Since the three sections A, B and C of the channel 25 are turned uponthemselves, i.e., the section B is at approximately 90 to the section Aand the section C is also at approximately 90 to the section B, forminggenerally a channel 25 of U-shape when viewed endwise, FIG. 2, any pullon the leads 27 and 29 will not be transferred to the winding but willtend to cause the part of the leads in the section B to jam furtherinwardly. This, together with the fact that the width of the channel 25is slightly less than the outside diameter of the insulation on theleads, transfers any force on the leads to the spool 10. Although thespool 10 has been illustratedand described as generally rectangular incross section, it is seen that this invention is applicable as well toother shapes for the spool, such as circular, for example. a

To further separate the soldered joint between the starting end wire 33and the lead wire 27 from the lead wire 29, the lead wire may be doubledback or hooked over so that the insulated part of the lead wire 27,shown in FIG. 6, just to the right of the soldered joint overlies thesoldered joint and separates it from the overlying part of the lead wire29.

Having described this invention, I claim:

1. A coil comprising aspool of electrically insulating material having acore and first, second and third end flanges, a winding of insulatedwire on the core between the first and second of said end flanges, saidwinding having a starting end wire and a finishing end wire extendingfrom the body of the winding, a bottom wall connecting the second andthird flanges and therewith defining a channel at one end of said spool,said channel being open along its outer peripheral extent, said channelbeing turned at an angle to itself along its length, a starting leadwire and a finishing lead wire connected to the starting end wire and tothe finishing end wire, and portions of the lengths of said lead wiresbeing disposed in said channel with at least one of the lead wires inwedgin-g relation with portions of the flanges.

2. The structure recited in claim 1 wherein said second flange isnotched at the entry end of the channel to define for the starting endwire a side entrance to said channel, and said bottom wall has a topsurface coplanar with the contiguous surface of the core at the entryend of the channel.

3. The structure recited in claim 2 wherein said core has a generallyrectangular shape in cross-section and said flange being turned uponitself in a U-shape and said notch is located at a corner of said secondflange.

4. The structure recited in claim 3 wherein the part of the bottom wallbetween the second and third flanges increases gradually to a greaterthickness than the thickness of the part of the bottom Wall between thenotch and the third flange.

5. The structure recited in claim 4 further defined by said channelbeing wide enough and deep enough in cross-section to accommodate bothlead wires without any of said lead wires extending radially outwardlyof said channel.

6. A spool of electrically insulating material having a core and first,second, and third end flanges, a bottom wall connecting the second andthird flanges and therewith defining a channel at one end of the spool,said channel being open ended and open along its outer peripheralextent, said channel being turned at an angle to itself along itslength, said second flange being notched at the entry end of saidchannel to define for a starting end wire a side entrance to saidchannel.

7. The structure recited in claim 6 wherein said channel has a U-shapeand said bottom wall has a top surface coplanar with the contiguoussurface of the core at the entry end of the channel, the open ends ofthe channel being formed by the ends of the U-shape.

8. The structure recited in claim 7 wherein said core and flanges have agenerally rectangular shape in crosssection and said notch is located ata corner of said second flange.

9. The structure recited in claim 8 wherein the part of the bottom Wallbetween the second and third flanges increases gradually to a greaterthickness than the thickness of the part of the bottom wall between thenotch and the third flange.

10. The method of making a coil comprising a spool and a windingcomprising placing a starting end wire in a channel of the spool,temporarily securing a part of the starting end wire to the spool,forming a Wire winding on the spool, placing an insulator on thewinding, laying the finishing end wire on the insulator, soldering thefinishing end Wire to the finishing lead Wire, securing a part of thefinishing lead Wire to the winding by covering said Winding and a partof said lead wire with insulating tape, unsecuring said starting endwire from its temporary attachment to said spool, soldering saidstarting end wire to said starting lead Wire, placing said starting endwire and forcing a part of said starting lead wire into said channel,and forcing a part of said finishing lead wire into said channel.

11. The method of making a coil comprising a spool and a Windingcomprising forming a wire winding on the spool, soldering the finishingend wire to the finishing lead wire, securing a part of the finishinglead wire to the winding by covering said winding and a pait of saidlead wire with insulating tape, soldering said starting end wire to saidstarting lead wire, placing said starting end Wire and forcing a part ofsaid starting lead Wire into a channel, and forcing a part of saidfinishing lead Wire into said channel.

12. The method of making a coil as recited in claim 10 and modified bysecuring the finishing end wire to the insulator and winding with a partof the finishing end wire being exposed and overlying the insulator, andthereafter soldering said finishing end wire to the finishing lead wire.

References Cited UNITED STATES PATENTS 2,661,446 12/1953 Adcock 29-115.5X 3,117,294 1/ 1964 Muskynski 336-2 O8 X 3,230,489 1/1966 Weyrich336-208 X 3,265,999 8/1966 Kessel 336-192 LEWIS H. MYERS, PrimaryExaminer.

E. GOLDBERG, Assistant Examiner.

